Create Spring ApplicationContextInitializer implementation and supporting class to disable bean definition overriding.

This ApplicationContextInitializer can be primarily used for testing purposes, especially to mimic the default behavior of the Spring container in a Spring Boot application context.

spring-data-geode/src/main/java/org/springframework/data/gemfire/support/DisableBeanDefinitionOverridingApplicationContextInitializer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.gemfire.support;
+
+import java.util.Optional;
+
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+
+/**
+ * Spring {@link ApplicationContextInitializer} implementation that disables the Spring container's
+ * ({@link ConfigurableApplicationContext}) default behavior of bean definition overriding.
+ *
+ * @author John Blum
+ * @see org.springframework.context.ApplicationContextInitializer
+ * @see org.springframework.context.ConfigurableApplicationContext
+ * @since 2.6.0
+ */
+public final class DisableBeanDefinitionOverridingApplicationContextInitializer
+		implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+	/**
+	 * @inheritDoc
+	 */
+	@Override
+	public void initialize(ConfigurableApplicationContext applicationContext) {
+
+		Optional.ofNullable(applicationContext)
+			.map(ConfigurableApplicationContext::getBeanFactory)
+			.filter(DefaultListableBeanFactory.class::isInstance)
+			.map(DefaultListableBeanFactory.class::cast)
+			.ifPresent(beanFactory -> beanFactory.setAllowBeanDefinitionOverriding(false));
+	}
+}

spring-data-geode/src/test/java/org/springframework/data/gemfire/support/DisableBeanDefinitionOverridingApplicationContextInitializerIntegrationTests.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.gemfire.support;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+/**
+ * Integration Tests for {@link DisableBeanDefinitionOverridingApplicationContextInitializer}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.springframework.beans.factory.config.ConfigurableListableBeanFactory
+ * @see org.springframework.context.ApplicationContextInitializer
+ * @see org.springframework.context.ConfigurableApplicationContext
+ * @see org.springframework.data.gemfire.support.DisableBeanDefinitionOverridingApplicationContextInitializer
+ * @see org.springframework.test.context.ContextConfiguration
+ * @see org.springframework.test.context.junit4.SpringRunner
+ * @since 2.6.0
+ */
+@RunWith(SpringRunner.class)
+@ContextConfiguration(initializers = DisableBeanDefinitionOverridingApplicationContextInitializer.class)
+@SuppressWarnings("unused")
+public class DisableBeanDefinitionOverridingApplicationContextInitializerIntegrationTests {
+
+	@Autowired
+	private ConfigurableApplicationContext applicationContext;
+
+	@Test
+	public void beanDefinitionOverridingIsNotAllowed() {
+
+		assertThat(this.applicationContext).isNotNull();
+
+		ConfigurableListableBeanFactory beanFactory = this.applicationContext.getBeanFactory();
+
+		assertThat(beanFactory).isInstanceOf(DefaultListableBeanFactory.class);
+
+		assertThat(((DefaultListableBeanFactory) beanFactory).isAllowBeanDefinitionOverriding()).isFalse();
+	}
+}

spring-data-geode/src/test/java/org/springframework/data/gemfire/support/DisableBeanDefinitionOverridingApplicationContextInitializerUnitTests.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.gemfire.support;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+import org.junit.Test;
+
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.context.ConfigurableApplicationContext;
+
+/**
+ * Unit Tests for {@link DisableBeanDefinitionOverridingApplicationContextInitializer}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.springframework.context.ApplicationContextInitializer
+ * @see org.springframework.context.ConfigurableApplicationContext
+ * @see org.springframework.data.gemfire.support.DisableBeanDefinitionOverridingApplicationContextInitializer
+ * @since 2.6.0
+ */
+public class DisableBeanDefinitionOverridingApplicationContextInitializerUnitTests {
+
+	private final DisableBeanDefinitionOverridingApplicationContextInitializer applicationContextInitializer =
+		new DisableBeanDefinitionOverridingApplicationContextInitializer();
+
+	@Test
+	public void initializeDisablesBeanDefinitionOverriding() {
+
+		ConfigurableApplicationContext mockApplicationContext = mock(ConfigurableApplicationContext.class);
+
+		DefaultListableBeanFactory beanFactory = spy(DefaultListableBeanFactory.class);
+
+		doReturn(beanFactory).when(mockApplicationContext).getBeanFactory();
+
+		assertThat(beanFactory.isAllowBeanDefinitionOverriding()).isTrue();
+
+		applicationContextInitializer.initialize(mockApplicationContext);
+
+		assertThat(beanFactory.isAllowBeanDefinitionOverriding()).isFalse();
+
+		verify(mockApplicationContext, times(1)).getBeanFactory();
+		verify(beanFactory, times(2)).isAllowBeanDefinitionOverriding();
+		verify(beanFactory, times(1)).setAllowBeanDefinitionOverriding(eq(false));
+		verifyNoMoreInteractions(mockApplicationContext, beanFactory);
+	}
+}